When Mr Lee is 42 years old, his son is 10 years old. In how many years will he be 3 times as old as his son?
| |
Mr Lee |
His son |
Difference |
| Before |
42 |
10 |
32 |
| Change |
+ ? |
+ ? |
|
| After |
3 u |
1 u |
2 u |
The difference in the age between Mr Lee and his son at first and in the end remains the same.
Difference in the age between Mr Lee and his son
= 3 u - 1 u
= 2 u
2 u = 42 - 10
2 u = 32
1 u = 32 ÷ 2 = 16
Number of years' time so Mr Lee will be 3 times as old as his son
= 16 - 10
= 6
Answer(s): 6
